This invention relates to a controller for use with a camera whereby the camera can be put into or be maintained in a state of maximum readiness whilst facilitating operator adjustment by means of a single control so as to allow a choice between depth of focus and the ability of the camera to freeze movement. By the expression "state of maximum readiness" is meant herein that the camera is enabled to take a correctly exposed photograph irrespective of the setting of the said control whenever the exposure value required lies within the range of exposure values corresponding to the shutter and lens of the camera.
Various mechanisms are already known to be incorporated in cameras for the purpose of controlling the shutter speed and the f-number in relation to the required exposure. Usually they are of one or other of two types, namely the so-called "shutter priority" system and the "f-number priority" system. With the shutter priority system the operator selects the shutter speed to his requirements and the said mechanism automatically selects the appropriate f-number for the available light and the speed of the film in use. With the f-number priority system the operator selects the f-number required and the mechanism takes care of the shutter speed. In both systems supervision of the camera setting by the operator is necessary and usually some manual adjustment thereof is required, even though the exposure value needed lies within the exposure value range of shutter and lens of the camera.
A somewhat less sophisticated system is known, called the "fully programmed" system which selects both f-number and shutter speed automatically. This system does maintain the camera in a state of maximum readiness but it denies the operator any control over the f-number and shutter speed. Such control is desirable because the operator may wish to vary the depth of focus or avoid blurring of the image on the film due to rapid movement of objects in the camera's field of view.
There is also a camera controller system known, built into a camera, which incorporates both the shutter speed priority system and the f-number priority system. A manually operated selector switch determines which of the two systems is to be operative. The operator sets the switch according to his choice of priority and then sets the required parameter, i.e. aperture or shutter speed of the camera, with the respective manual control. A digital computer incorporated in the camera then determines the setting of the other parameter for the instant brightness (i.e. the setting of the shutter speed or the aperture respectively) where it is possible to do so. If the calculated setting of the second said parameter is outside the range of the camera, and therefore impossible, the controller sets it at the limiting value (maximum or minimum as the case may be), recalculates the first said parameter for optimum performance, and resets the latter automatically.
With the present invention the operator has only one variable control to concern himself with, namely the bias setting. For all acceptable values of brightness for the camera, an internal controller automatically selects an optimum set of f-number and shutter speed values and provides f-number and shutter speed setting signals in which the relationship of f-number and shutter speed is a function of the bias setting. A uniform variation of f-number and shutter speed settings over the whole of the bias setting range is provided and when the operator wishes to alter the relationship of these two parameters he has only to alter the bias control to a new setting. The controller may be arranged such that the camera is always in a state of maximum readiness without it being necessary for the operator to make any form of adjustment of the aperture and shutter controls.
Thus it is an object of this invention to provide a new and improved controller for a camera.
It is a further object of this invention to provide controller means which will enable the camera operator to maintain his camera in a state of maximum readiness yet facilitate continuous operator control over the depth of focus and the ability of the camera to freeze movement.